ICL 4.8: Congenital Heart Disease Anatomy & Clinical Syndromes

Question 1

what is a congenital heart defect?

Answer 1

congenital heart defects are structural abnormalities present at birth that MAY result in alteration of heart function

Question 2

what is the mechanism behind congenital heart defects?

Answer 2

faulty embryonic development:

1. misplaced structures (TGA)

the aorta and pulmonary artery don’t always twist and they form transpositional great arteries where the aorta is connected to the right ventricle and pulmonary trunk is connected to the left ventricle

2. arrest in the progression of a normal structure from an early stage to a more advanced one (ASD)

if the septum secundum doesn’t develop you’ll get an atrial septal defect

Question 3

what is the etiology of congenital heart defects?

Answer 3

1. single gene defect
2. environmental factors
3. viral exposure
4. maternal ingestion of toxic substances
5. unknown

Question 4

viral exposure to which virus can cause a patent ductus arteriosus?

Answer 4

rubella

Question 5

what is the most common congenital defect?

Answer 5

ventricular septal defect

least common is tricuspid atresia

Question 6

what are the common features of congenital heart defects?

Answer 6

1. history of early onset of cardiac symptoms such as birth (blue baby)
2. loud murmur with a thrill along the left sternal border
3. cyanosis with intense dyspnea on exertion early in childhood
4. failure of normal growth and development
5. rapid heart rate (160 to 180 beats per minute)
6. pulmonary wheezing

Question 7

what is cyanosis?

Answer 7

cyanosis results when the blood contains more than 5 grams of reduced hemoglobin/100 mL

cyanosis is recognizable by a purplish to bluish tinge to the skin in areas with dense superficial capillary circulation like the nails and lips

cyanosis is a common features of congenital heart defect

Question 8

which congenital heart defects are associated with cyanosis?

Answer 8

1. transposition of the great vessels
2. tetralogy of fallot
3. tricuspid atresia
4. severe septal defect
5. severe pulmonic stenosis

Question 9

how are congenital heart defects classified?

Answer 9

Maude Abbott grouped cases in three categories according to the presence or absence of cyanosis

another more contemporary classification divides the cases into groups according to the presence and absence of a shunt

Question 10

what is cyanose tardive?

Answer 10

initial left to right shunt with late reversal of the flow

so it used to be acyanotic but now it’s cyanotic

Question 11

which congenital heart defects are associated with an initial left to right shunt?

Answer 11

1. ventricular septal defect
2. atrial septal defect
3. patent ductus arteriosus
4. persistent truncus arteriosus

Question 12

which congenital heart defects are associated with an initial right to left shunt?

Answer 12

tetralogy of fallout

Question 13

which congenital heart defects are associated with no shunt?

Answer 13

1. transposition of the great vessels
2. coarctation of the aorta
3. pulmonary stenosis
4. aortic stenosis

Question 14

what is a VSD?

Answer 14

VSD = ventricular septal defect

it’s an abnormal opening in the ventricular septum that occur as an isolated lesion, or in combination with other congenital heart anomalies

VSD is a consequence of a failure of the interventricular septum to form

it is a common defect (30% of congenital heart diseases) with an incidence of 0.1% - 0.2% in the general population

Question 15

what are the 2 types of VSDs?

Answer 15

1. membranous VSD
2. muscular VSD (less common)

VSDs may occur anywhere along the interventricular septum, but are most commonly located in the membranous portion of septum

Question 16

how does the BP, O2 saturation and mean pressure change in a heart with a VSD?

Answer 16

blood will flow from the left to right ventricle so there will be reduced pressure in the LV

that also means that there will be increased oxygen saturation in the RV since oxygenated blood from the LV is flowing into it

Question 17

what is an ASD?

Answer 17

ASD = atrial septal defect

ASD is an opening in the atrial septum caused by excessive resorption around the foramen secundum or hypoplastic growth of septum secundum (it’s too short)

it can occur anywhere along the the atrial septum, but the most common site is the midportion of the interatrial septum, in the region of the fossa ovale, termed an ostium secundum ASD

5-10% of congenital heart diseases; M/F = 1:2

Question 18

what are the 3 types of ASD?

Answer 18

1. ostium secundum defect (most common)

the septum secundum is mostly gone and blood just flows from the LA to RA through the ostium secundum

2. ostium primum defect

septum premium doesn’t develop and blood flows through the foramen ovale

3. sinus venosus defect

there’s just a hole at the top of what’s supposed to be the atrial septum

Question 19

what are the symptoms and PE findings of someone with an ASD?

Answer 19

most infants are asymptomatic

it’s detected by a murmur when the kids become school-age

most common symptom in adult is the development of palpitations

prominent systolic impulse may be palpated along the lower left sternal border

asystolic murmur may be present

mid-diastolic murmur may also be present at the lower left sternal border

Question 20

what is a PDA?

Answer 20

PDA = patent ductus arteriosus

PDA results when the Ductus Arteriosus fails to close after birth

the result is a persistent connection between aorta and pulmonary trunk

it can be life-threatening or life saving! –> if you have a PDA that’s really large so the shunt from the aorta to the pulmonary trunk decreases the blood going to the lungs which isn’t good –> however, if you have both a PDA and also happen to have transposition of the great vessels then the circulation is mixed and the only thing keeping the baby alive is the PDA

M:F = 1:3

frequently associated with maternal rubella infection during early pregnancy

Question 21

how does the ductus arteriosus close normally?

Answer 21

when the baby is born and the lungs start working, they release bradykinin and allow for high O2 levels which both cause the ductus arteriosus to constrict and close

Question 22

what medication do you give to close a PDA?

Answer 22

indomethacin!

it helps close the ductus arteriosus

Question 23

what medication do you give to keep a PDA open?

Answer 23

prostaglandin

Question 24

what is a CoA?

Answer 24

CoA = coarctation of aorta

coarctation is a pathologic narrowing of the aortic lumen that can occur anywhere along its length

M:F 2:1

Question 25

what are the 2 types of coarctations of the aorta?

Answer 25

based on the location of the ductus arteriosus:

1. PREDUCTAL
   occurs when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart and aortic isthmus, resulting in hypoplastic development of the aorta
2. POSTDUCTAL
   develops postnatally. It is most likely the result of muscular ductus arteriosus tissue extending into the aorta during fetal life; when ductal tissue constricts following birth, the ectopic tissue within the aorta also constrict, creating a “napkin ringlike” obstruction in the aorta

it is most commonly observed distal to the left subclavian artery, in the region near the ductus arteriosus

Question 26

what are the symptoms of preductal coarctation of the aorta?

Answer 26

1. congestive heart failure shortly after birth
2. HTN in upper extremities and pressure reduced in lower extremities
3. there’s differential cyanosis if the dustus arterosus remains open –> upper half of the body is perfused with oxygen while the lower half appears cyanotic

if the ductus arteriosus is open, as the aorta constricts the pressure will drop so then the pressure in the pulmonary is higher and deoxygenated blood from the pulmonary trunk will flow into the aorta causing cyanosis

preductal CoA occurs when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart and aortic isthmus, resulting in hypoplastic development of the aorta

Question 27

what are the symptoms of postductal coarctation of the aorta?

Answer 27

in the majority of newborns, the obstruction is not severe and these patients grow and mature normally

if defect is severe the newborn develop congestive heart failure from pressure overload –> if the ductus is open then most of the blood going through the aorta will go to the pulmonary trunk which increases the amount of blood going to the lungs and the LV is going to have to push really hard to get all that blood there and that’s how you get pressure overload

within the first weeks of life the infants present with tachypnea, dyspnea, tachycardia and hepatomegaly

Question 28

what is tetralogy of fallot?

Answer 28

The Tetralogy of Fallot is characterized
by a group of cardiac malformations
that result from a single defect: an abnormal anterosuperior and rightward displacement of the infundibular septum, resulting in an unequal division of the bulbus cordis into pulmonary and aortic outflow tracts

basically the aorta gets too greedy and loops a little extra so that it invades the space of the pulmonary trunk which reduces the size of the pulmonary trunk

this is the only congenital heart defect with a right to left shunt because the hypertrophy of the right ventricle increases pressure plus a VSD means blood is getting shunted from the RV to LV

Question 29

what are the 4 anomalies associated with tetralogy of fallot?

Answer 29

1. ventricular septal defect due to septum misalignment
2. subvalvular pulmonic stenosis because of obstruction of the infundibular septum
3. an overriding (dextroposed) aorta receives blood from both ventricles
4. right ventricular hypertrophy due to the high pressure load of the pulmonic stenosis

PROV = pulmonic stenosis, RV hypertrophy, overarching aorta, VSD

slide 36

Question 30

what are the symptoms of tetralogy of fallot?

Answer 30

1. dyspnea on exertion or when crying –> because it increases the pressure in the hypertrophic RV
2. “Tet spells” may occur following exertion or feeding
3. convulsions due to cerebral hypoxemia
4. children alleviate symptoms by “squatting”
5. children with moderate pulmonary stenosis are often mildly cyanotic
6. children with severe pulmonary stenosis present cyanosis in the first days of life
7. systolic murmur heard best at the left upper sternal border

Question 31

what is TGA?

Answer 31

TGA = transposition of the great arteries

TGA is present when the great vessels inappropriately arise from the opposite ventricle, that is, the aorta originates from the right ventricle and the pulmonary artery originates from the left ventricle

precise cause remains unknown; it may result of failure of the aorticopulmonary septum to spiral in a normal fashion during heart development

recently it has been suggested that the defect may be a result of abnormal growth and absorption of the subpulmonary and subaortic infundibuli during the division of the truncus arteriosus

Question 32

what could save a baby from dying if they have TGA?

Answer 32

if they also have a VSD and ASD it’ll help sort of restore normal circulation

Question 33

what is PTA?

Answer 33

PTA = persistent truncus arterosus

PTA is a congenital cardiac defect that can be explained as the result of absent or incomplete partitioning of the truncus arteriosus by the spiral septum, thus leaving a common trunk for the origin of the aorta, pulmonary arteries, and coronary arteries

basically it’s a neural crest defect because the neural crest didn’t seed the septum to form the aorta and pulmonary trunk so they just share a common trunk and blood from both the LV and RV flows into the common trunk and the degree of cyanosis just depends on the position of the trunk and how big it is

there are several variants of truncus arteriosus –> type 1 is the most common variant and consists of a single trunk that gives rise to a common pulmonary artery and ascending aorta